Expression of NPAT, a novel substrate of cyclin E-CDK2, promotes S-phase entry.
To understand the mechanisms by which CDKs regulate cell cycle progression, it is necessary to identify and characterize the physiological substrates of these kinases. We have developed a screening method to identify novel CDK substrates. One of the cDNAs identified in the screen is identical to the recently isolated NPAT gene. Here we show that NPAT associates with cyclin E-CDK2 in vivo and can be phosphorylated by this CDK. The protein level of NPAT peaks at the G1/S boundary. Overexpression of NPAT accelerates S-phase entry, and this effect is enhanced by coexpression of cyclin E-CDK2. These results suggest that NPAT is a substrate of cyclin E-CDK2 and plays a role in S-phase entry.
Zhao
J
J
Laboratory of Molecular Oncology, Massachusetts General Hospital (MGH) Cancer Center, Charlestown, Massachusetts 02129, USA. zhao@helix.mgh.harvard.edu
Dynlacht
B
B
Imai
T
T
Hori
T
T
Harlow
E
E
D042846:CDC2-CDC28 Kinases; D018797:Cell Cycle Proteins; D019927:Cyclin E / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016193:G1 Phase / Q000502:physiology; D015723:Gene Library; D006801:Humans; D009687:Nuclear Proteins; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D016196:S Phase / Q000502:physiology*; D012641:Selection, Genetic; D013379:Substrate Specificity
D018797:Cell Cycle Proteins; D019927:Cyclin E; C101693:NPAT protein, human; D009687:Nuclear Proteins; D011506:Proteins; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases